In the parent program project we had hypothesized that AC5 disruption (knock out, KO) was a model of longevity and planned to compare it to the most widely studied model of longevity, caloric restriction (CR). We hypothesized that the combination of AC5 KO and CR might result in even greater longevity, if there were sufficiently different mechanisms involved that could act synergistically. In the first two years of the program project the testing of this hypothesis resulted in dramatically different results, i.e., the AC5 KO mice with superimposed CR all died within one month. The goal of this revised application is to investigate the mechanisms in depth mediating this lethal combination, since the shared molecular and cellular mechanisms are likely the key molecular mechanisms mediating longevity and stress resistance. Since both models demonstrate significant alterations in metabolism, first we will examine the major mechanisms involved in response to limited caloric intake or to enhanced metabolism, e.g., glucose utilization, depletion of glycogen stores, and utilization of fatty acids. Next we will examine the molecular mechanisms shared by these major models of longevity and stress resistance by genomic and proteomic investigation. To accomplish this we are proposing a fourth Project for this Program Project. The new project ('Common Longevity Mechanisms in Caloric Restriction and AC5 Knockout') will also utilize all the Cores (Core A: Administration/ Physiology, Core B: Animal Care, Core C: Proteomics/Genomics, Core D: Bioinformatics/Biostatistics and Core E: Pathology). The central hypothesis of this revised revision application is that AC5 inhibition and CR induce longevity and stress resistance through similar mechanisms, and that this project will identify the shared mechanisms, which are both common and unique, mediating longevity and stress resistance. Specific Aim 1: To examine glucose and fatty acid metabolism in blood, liver, heart, skeletal muscle and adipose tissue in AC5 KO mice and compare to WT with moderate and severe caloric restriction. A second goal will be to compare the effects of superimposition of the two levels of CR in AC5 KO. Specific Aim 2: To determine the cause of death in AC5 KO mice with superimposition of CR using pathology, histology and biochemistry. Specific Aim 3: To determine shared molecular mechanisms that regulate longevity, stress resistance and metabolism in AC5 KO and CR using genomic and proteomic approaches.